An organic polymer having at least one reactive silyl group per molecule is known to have a characteristic that it is cross-linked by siloxane bond formation involving hydrolysis or other reactions of the silyl group due to factors such as moisture even at room temperature, whereby a rubbery cured product is obtained.
Among such polymers, polymers containing an alkyldialkoxysilyl group are known to offer excellent, flexible and tough cured products and are widely used in applications such as sealants, adhesives, and coating agents. Curable compositions containing these organic polymers are usually cured by means of a condensation catalyst such as a dibutyltin compound. In the case that such a curable composition needs to be cured in a short time, generally, for example, the amount of condensation catalyst is increased. However, the toxicity of organotin compounds has been pointed out in recent years, and these compounds must be used with care from the viewpoint of environmental safety.
Although polymers having a trialkoxysilyl group at both terminals have high curability, the resulting cured products are known to be hard and brittle. In the case of using these polymers for contact adhesives, the crosslink density becomes too high during curing, which causes the problem that the length of time until tack development (i.e., so-called open time) cannot be long.
Meanwhile, it has been suggested that the use of a polymer having a specific terminal structure, although terminated with a dialkoxysilyl group, can provide a curable composition having a high curing rate (Patent Literature 1 and Patent Literature 2). In some cases, however, the curable compositions prepared from the polymers described in Patent Literatures 1 and 2 give cured products having poor tensile properties.